Drip irrigation emitters can be used on relatively low pressure fluid supply lines (e.g. lines having a pressure between about 0.5 to 4 bar) to deliver water and/or nutrients directly to individual plants. To use, each emitter may be inserted into and bonded to the water line at regular intervals or can be mounted on the outside of the line, for example, using a barbed stem formed on the emitter. In this way, each emitter acts as a point source of water for each plant. Because emitter systems only deliver irrigation water to locations where water is needed, these systems conserve water as compared with conventional watering systems which cover a wide area with water. In addition, emitter systems generally experience less evaporative losses as compared to conventional watering systems.
As the fluid in an emitter system travels through the supply line away from the fluid source, the pressure in the line decreases. Stated differently, the fluid pressure is greatest where fluid enters the supply line and the pressure gradually decreases with distance therefrom. This pressure drop occurs due to frictional forces that develop between the flowing water and supply line and because water is being emitted along the length of the line. In addition, other factors such as elevation can also result in fluid pressure variations. When non-pressure compensating emitters are used, the drip rate also varies and is unstable due to the variation in pressure along the line. These changes in drip rate can be problematic because some plants will receive more fluid than others. To be expected, it is desirable that all emitters have a relatively uniform drip rate along the length of the fluid line. To overcome the variation in drip rate that occurs with non-pressure compensating emitters, typically only relatively short fluid lines are employed when using non-pressure compensating emitters.
To reduce the ill-effects caused by variations in line pressure, pressure compensating drip irrigation emitters (also referred to as so-called “flow regulated emitters”) have been developed that produce a somewhat uniform flow over a range of line pressures. With pressure compensation, longer fluid lines can be employed while still providing substantially uniform drip rates. This, in turn, allows for large areas to be irrigated with a relatively low flow rate in the supply line. Because only a low flow rate is required in the supply line when using pressure compensating drip irrigation emitters, the energy cost of pumps and associated equipment is minimized.
One important factor worthy of consideration when using irrigation emitters is water filtration. In this regard, it can be important to properly filter fluid from the supply line to avoid clogs within the emitter and increase the emitter's lifespan. This, in turn, implies that the emitter includes a relatively large filtering area to ensure a sufficient volume of filtered fluid is available for processing by the emitter. Proper filtration is essential because debris or other matter present in the fluid line can block or restrict flow through the emitter reducing output flow.
It is also desirable to reduce or minimize the size and thickness of drip emitters for several reasons. For one, reducing the size and thickness of an emitter is advantageous because it results in savings in the cost of materials. Low cost drip emitters, in turn, allow for single use applications, in which a fluid line may be removed from the field for disposal or recycling after one or more growing seasons. In addition, reducing the size and thickness of an emitter simplifies and lowers the cost of packaging and shipping. Also, for fluid lines having an integrated emitter, it is a common procedure to roll the fluid line for packaging and shipping. However, each emitter has a thickness that may cause a bulge or lump that increases the difficulty of rolling and packaging the fluid line, especially for thin walled fluid lines. With this in mind, a drip irrigation emitter is needed having reduced size and thickness to facilitate packaging and shipping of thin walled drip tape or conduit.
In light of the above it is an object of the present invention to provide a pressure compensating drip emitter having a relatively small thickness to reduce material costs and improve shipping and handling characteristics. It is another object of the present invention to provide a pressure compensating drip emitter having a relatively small thickness and a relatively large filtering area to ensure that a proper supply of filtered fluid is provided for processing by the emitter. Still another object of the present invention is to provide a pressure compensating drip irrigation emitter having a relatively small thickness that can perform with sufficient pressure compensation in relatively low fluid line pressures to allow reduced operational cost by allowing low energy consumption water pumps. It is yet another object of the present invention to provide a pressure compensating drip irrigation emitter which is easy to use, relatively simple to manufacture, and comparatively cost effective.